$time = "$1:$2:$3.$4"
    if $time =~ /^(\d{2})(\d{2})(\d{2})\.(\d{2})/;

##</code><code>##

if($time =~ /^(\d{2})(\d{2})(\d{2})\.(\d{2})/) {
    $time = "$1:$2:$3.$4";
}
else {
    die "Malformed time: $time\n";
}